Method for the production of a continuous elastomeric film

Abstract

The present invention relates to method for the production of a continuous elastomeric film and to continuous elastomeric films and elastomeric articles obtained thereby, where the method comprises: B) providing an aqueous polymer latex composition comprising: (I) particles of a latex polymer obtained by free-radical emulsion polymerization of a mixture of ethylenically unsaturated monomers, the particles bearing a plurality of functional groups, and (II) a crosslinking component comprising a plurality of functional groups at least one thereof being reactive with the functional groups on the latex polymer particles; B) forming from the aqueous polymer latex composition a continuous polymer film; C) optionally drying the continuous polymer film obtained in step B); D) curing the continuous polymer film obtained in step B) or C) to form a continuous elastomeric film; and E) optionally rolling the continuous elastomeric film obtained in step D) into a roll.

The invention claimed is: 
     
       1. A method for the production of a continuous elastomeric film comprising:
 A) providing an aqueous polymer latex composition comprising:
 (I) particles of a latex polymer obtained by free-radical emulsion polymerization of a mixture of ethylenically unsaturated monomers, the particles bearing a plurality of functional groups, and 
 (II) a crosslinking component comprising a plurality of functional groups, at least one thereof being reactive with the functional groups on the latex polymer particles; 
 
 B) forming from the aqueous polymer latex composition a continuous polymer film or an elastomeric material; 
 C) optionally drying the continuous polymer film obtained in step B); 
 D) curing the continuous polymer film obtained in step B) or C) to form a continuous elastomeric film; and 
 E) optionally rolling the continuous elastomeric film obtained in step D) into a roll, wherein 
 the cured film or elastomeric material comprises thermally reversible linkages selected from one or more of 
 (i) a linkage having the structural formula 
 
       
         
           
           
               
               
           
         
         
           wherein: X is —O— or —NR 1 —,
 n is 0 or 1, 
 R 1  is hydrogen or a hydrocarbyl group, and 
 R 2  is a hydrocarbyl group; and 
 
         
         (ii) a beta-hydroxy ester linkage, wherein
 the aqueous polymer latex composition in step (B) is cast on a substrate at a preselected thickness, then cured to form the elastomeric film followed by stripping the obtained elastomeric film from the substrate; or 
 the aqueous polymer latex composition is treated to promote coagulation of the latex composition, the aqueous polymer latex composition is diluted to a preselected solids content that correlates to the preselected thickness of the film, and in step (B) a heated or cooled roll is contacted with the aqueous polymer latex composition to coagulate a polymer film on the roll surface, followed by curing the film to form the elastomeric film and stripping the obtained elastomeric film from the roll; or 
 the aqueous polymer latex composition is diluted to a preselected solids content that correlates to the preselected thickness of the film, a heated roll is contacted with a coagulant solution comprising multivalent cations and dried, subsequently in step (B) the heated roll is contacted with the aqueous polymer latex composition to coagulate a polymer film on the roll surface, followed by curing the film to form the elastomeric film and stripping the obtained elastomeric film from the roll; or 
 by forming the elastomeric material into a continuous film by subjecting the material to a pressure of 1-20 MPa and a temperature of 40° C. to 200° C. and optionally rolling the continuous elastomeric film into a roll. 
 
       
     
     
       2. The method of  claim 1 , wherein the mixture of ethylenically unsaturated monomers for latex polymer (I) comprises:
 a) 15 to 99 wt.-% of conjugated dienes; 
 b) 1 to 80 wt.-% of ethylenically unsaturated nitrile compounds; 
 c) 0.05 to 10 wt.-% of ethylenically unsaturated compounds bearing functional groups (a); 
 d) 0 to 80 wt.-% of vinyl aromatic monomers; and 
 e) 0 to 65 wt.-% of co-polymerizable ethylenically unsaturated compounds, 
 wherein monomers a) to e) are different from each other and the weight percentages being based on the total monomers in the mixture. 
 
     
     
       3. The method of  claim 1 , wherein the aqueous polymer latex composition comprises:
 (I) particles of a latex polymer obtained by free-radical emulsion polymerization of a mixture of ethylenically unsaturated monomers, said particles bearing a plurality of functional groups (a), and 
 (II) a crosslinking component comprising a plurality of functional groups selected from functional groups (b) or a combination of functional groups (b) and (c) that are different from each other, wherein
 functional group (b) forms upon reaction with functional group (a) a thermally reversible linkage selected from one or more of 
 (i) a linkage having the structural formula 
 
 
       
         
           
           
               
               
           
         
         
           
             wherein: X is —O— or —NR 1 —,
 n is 0 or 1, 
 R 1  is hydrogen or a hydrocarbyl group, and 
 R 2  is a hydrocarbyl group; 
 
             and 
           
           (ii) a beta-hydroxy ester linkage; and 
           functional groups (c) on different molecules of component (II) are capable of reacting with each other. 
         
       
     
     
       4. The method of  claim 2 , wherein
 a) the conjugated dienes are selected from butadiene, isoprene, 2,3-dimethyl-1,3-butadiene, 2-ethyl-1,3-butadiene, 1,3-pentadiene, myrcene, ocimene, farnesene and combinations thereof, 
 b) the ethylenically unsaturated nitrile compounds are selected from (meth)acrylonitrile, alpha-cyanoethyl acrylonitrile, fumaronitrile, alpha-chloronitrile and combinations thereof; 
 c) the ethylenically unsaturated compounds bearing functional group (a) are selected from
 ethylenically unsaturated compounds bearing a functional group having the structure: 
 
 
       
         
           
           
               
               
           
         
         
           wherein X, n, R 1  and R 2  are defined; 
           ethylenically unsaturated compounds having a primary amino group; 
           ethylenically unsaturated oxirane compounds; 
           ethylenically unsaturated carboxylic acids and salts thereof, 
           ethylenically unsaturated polycarboxylic acid anhydride; 
           polycarboxylic acid partial ester monomers and salts thereof; and 
         
         d) the vinyl aromatic monomers are selected from styrene, alpha-methyl styrene, vinyl toluene and combinations thereof; 
         e) the co-polymerizable ethylenically unsaturated compounds are selected from
 e1) alkyl esters of ethylenically unsaturated acids; 
 e2) hydroxyalkyl esters of ethylenically unsaturated acids; 
 e3) amides of ethylenically unsaturated acids; 
 e4) vinyl carboxylates; 
 e5) alkoxyalkyl esters of ethylenically unsaturated acids; and 
 
         the function group (b) is selected from an oxirane group, a carboxylic acid group, salt or anhydride thereof, a primary amine group and a functional group having the structure: 
       
       
         
           
           
               
               
           
         
         wherein X, n, R 1  and R 2  are defined. 
       
     
     
       5. The method of  claim 2 , wherein
 the functional group (a) is a carboxylic acid group, a salt or anhydride thereof; 
 functional group (b) is an oxirane group, and 
 functional group (c) if present is selected from
 silane groups bearing a plurality of silicon bonded hydroxyl groups and/or hydrolysable groups; and 
 ethylenically saturated groups. 
 
 
     
     
       6. The method of  claim 2 , wherein the latex polymer (I) and the crosslinking component (II) are present in relative amounts to provide a molar ratio of functional groups (b) to functional group (a) from 0.1 to 2. 
     
     
       7. The method of any of  claim 2 , wherein the crosslinking component (II) is selected from
 polyoxirane functional latex particles, 
 polyoxirane functional monomeric or oligomeric compounds; 
 oxirane functional ethylenically unsaturated compounds; 
 oxirane functional di- or tri alkoxysilanes; 
 primary amino functional di- or tri alkoxysilanes. 
 
     
     
       8. The method of  claim 1 , wherein the latex polymer (I) has a gel content of less than 70 wt.-%. 
     
     
       9. The method of  claim 1 , wherein the aqueous polymer latex composition further comprises adjuvants selected from antifoams, wetting agents, thickeners, plasticizers, fillers, pigments, dispersants, optical brighteners, antioxidants, biocides and metal chelating agents and combinations thereof and the pH of the aqueous polymer latex composition is optionally adjusted to be in the range of 8.5 to 13. 
     
     
       10. The method of  claim 1 , wherein the elastomeric material is made from the aqueous polymer latex composition as defined. 
     
     
       11. A continuous elastomeric film obtainable by the method of  claim 1 . 
     
     
       12. The continuous elastomeric film of  claim 11  having a thickness of 0.03 to 3.00 mm. 
     
     
       13. A process for making an elastomeric article by
 aligning two separate continuous elastomeric films according to  claim 11 ; 
 cutting the aligned continuous elastomeric films into a preselected shape to obtain two superposed layers of the elastomeric films in the preselected shape; and 
 joining together the superposed layers of elastomeric film at at least a preselected part of the periphery of the superposed layers to form an elastomeric article. 
 
     
     
       14. The process of  claim 13 , wherein the joining together is performed by using thermal means or by gluing. 
     
     
       15. The process of  claim 13 , wherein the cutting is performed by a heatable template cutting device or laser cutter, providing the preselected shape and the cutting device is heated in the sections that contact the elastomeric films where the films are joined together, thereby simultaneously cutting the elastomeric films into the preselected shape and heat sealing the preselected parts of the periphery of the superposed elastomeric films. 
     
     
       16. An article obtained by the process of  claim 13 . 
     
     
       17. The article of  claim 16  being selected from surgical gloves, examination gloves, industrial gloves, and household gloves, single-use gloves, textile supported gloves, catheters, elastomeric sleeves and condoms.